A drawer is divided into 9 square boxes, creating a 3*3 grid.
Your task is to create a "magic square" by putting a distinct amount of money in each of the boxes in a way that all of the 8 sums (vertical, horizontal and diagonal) will be the same.
Only standard American coins are allowed, i.e. 1,5,10,25,50, and 100c.

What is the minimal amount of coins ?
Show their distribution.

(In reply to A better solution? (Thinking outside the box) by Steve Herman)

Not an improvement, but an alternate solution with a 0 cent box permitted. Instead of nickels, dimes, and quarters, a solution of 14 coins with quarters, half-dollars, and dollar coins is possible:

 25  200   75
150 100   50
125    0  175

       25   100+100          50+25
100+50          100                50
100+25             0   100+50+25   
     
 

Posted by Dej Mar on 2020-08-13 04:50:11